The present invention relates to improvements in apparatus for testing cigarettes and analogous rod-shaped articles. More particularly, the invention relates to improvements in apparatus for testing the tubular wrappers of cigarettes or analogous rod-shaped articles (hereinafter called cigarettes or filter cigarettes for short) for the presence or absence of leaks including open seams, holes and frayed ends, for the condition of seals between the filter mouthpieces and tobacco-containing portions of filter cigarettes, for the extent of permeability of cigarette paper and/or for the extent of permeability of so-called ventilation or aerating zones including intentionally made holes provided in the wrappers of filter rod sections for admission of cool atmospheric air into the column of tobacco smoke. Still more particularly, the invention relates to improvements in cigarette testing apparatus of the type wherein a stream of testing air is admitted into one or both axial ends of a cigarette during travel through the testing station and while the respective end portion of the peripheral surface of the wrapper is sealingly engaged by an elastic sealing element.
Apparatus of the above outlined character are disclosed in the aforementioned U.S. Pats. Nos. 3,769,832 and 3,914,989. It is also known to install the sealing elements on rotary carriers which are mounted not unlike the wobble plates of certain types of pumps so that each sealing element moves toward the adjacent end portion of a cigarette to be tested during one half and moves away from such end portion during the other half of each revolution of the respective carrier. This ensures that the end portions of cigarettes are received in the adjacent sealing elements during admission of testing fluid into their fillers. The sealing elements consist of rubber or a similar elastomeric material and their inner diameters are variable so that they can be deformed into sealing engagement with the peripheral surfaces of wrappers forming part of cigarettes which are being transported toward and through the testing station.
Highly accurate testing of the wrappers for the permeability or the presence of leaks is particularly important when the filters of filter cigarettes are provided with aforementioned ventilation or aerating zones in order to admit predetermined quantities of air into the column of tobacco smoke. An important prerequisite for accurate testing is proper sealing of the end portions of the wrappers against entry of atmospheric air and/or against escape of testing fluid into the surrounding atmosphere. Even minor leaks at the ends of the wrappers are likely to greatly distort the results of measurements and can result in ejection of satisfactory cigarettes or in the failure to eject defective cigarettes.
In accordance with heretofore known proposals, elastically deformable sealing elements are moved into sealing engagement with the ends of cigarette wrappers by pneumatic deforming means or by resorting to reciprocable sleeves, plungers or analogous mechanical deforming elements. Such mode of deforming the elastic sealing elements is complex, expensive and not sufficiently reliable to ensure satisfactory testing of the wrappers which are formed with ventilation zones. It was further proposed to bias the end faces of cigarettes against sealing elements with a force which should suffice to prevent uncontrolled escape of testing fluid prior to penetration into the fillers of cigarettes (note, for example, FIGS. 7 and 8 of U.S. Pat. No. 3,914,989). Such mode of testing is highly likely to entail damage to (especially undesirable deformation of) the end portions of cigarettes.